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A-level Computer Science
Algorithm efficiency and Big-O notation
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Cards (44)
What does algorithm efficiency measure?
The time based on
input size
What does algorithm efficiency describe?
How
fast
an
algorithm runs
How do the different categories of running time complexity compare in terms of efficiency?
The categories are ordered from most efficient (
O(1)
- Best) to least efficient (
O(n!)
,
O(n^n)
,
O(n^c)
- Worst).
How do efficient algorithms reduce resource usage?
They minimize
energy consumption
and
memory needed
What is the x-axis label in the image?
Input
Size
n
Why is algorithm efficiency important?
It saves time, reduces resource usage, and improves scalability
Why is understanding Big O notation important?
Helps choose efficient algorithms
Allows comparison of algorithm
performance
Aids in predicting runtime based on input size
How does the running time complexity of an algorithm with O(n) scale as the input size increases, compared to an algorithm with O(logn)?
O(n) scales
linearly
with input size, while O(logn) scales
logarithmically
, making O(logn) more efficient for large inputs
Which Big O time complexity is the slowest?
O
(
2
n
)
O(2^{n})
O
(
2
n
)
What is the Big-O notation for Binary Search?
O
(
log
n
)
O(\log n)
O
(
lo
g
n
)
What does
O
(
n
2
)
O(n^{2})
O
(
n
2
)
represent in Big O notation?
Quadratic time
What is the growth rate of
O
(
1
)
O(1)
O
(
1
)
?
Constant
Which Big O time complexity is the fastest?
O
(
1
)
O(1)
O
(
1
)
What are the key reasons for algorithm efficiency's importance?
Saves time
Reduces resource usage
Enables
scalability
Improves user experience
What does
O
(
n
)
O(n)
O
(
n
)
signify in Big O notation?
Linear time
Why is Binary Search faster for large datasets?
It eliminates
half
the numbers each time
How does the time taken grow as input size increases?
At different rates along the
curves
How does Big O notation help in algorithm comparison?
It simplifies comparing different algorithms'
efficiency
What is the second search algorithm mentioned?
Binary Search
What does
O
(
1
)
O(1)
O
(
1
)
represent in Big O notation?
Constant time
What does
O
(
n
)
O(n)
O
(
n
)
signify in Linear Search?
Time increases
proportionally
with input size
What are the growth rates of the worst time complexities?
Quadratic
and
Exponential
How does Binary Search find the target?
It divides the
sorted
list in
half
repeatedly
Why is algorithm efficiency beneficial for mobile devices?
It minimizes
energy consumption
and
memory usage
Compare the efficiency of Linear Search and Binary Search.
Linear Search:
Checks each element sequentially
Big-O
notation
:
O
(
n
)
O(n)
O
(
n
)
Example: 1000
steps
for 1000
numbers
Binary Search:
Divides the list in half repeatedly
Big-O notation:
O
(
log
n
)
O(\log n)
O
(
lo
g
n
)
Example: 10 steps for 1000 numbers
How do efficient algorithms save time?
They
complete
tasks
faster
with
larger
datasets
What characterizes an inefficient algorithm?
Takes longer, especially with
larger
inputs
What is the growth rate of
O
(
n
)
O(n)
O
(
n
)
?
Linear
How does Linear Search operate?
It checks each
element
one
by one
What is the Big-O notation for Linear Search?
O
(
n
)
O(n)
O
(
n
)
What is the growth rate of
O
(
n
log
n
)
O(n \log n)
O
(
n
lo
g
n
)
?
Linearithmic
How does algorithm efficiency enable scalability?
It allows systems to handle
massive
traffic without slowdowns
What is the time complexity of linear search?
O
(
n
)
O(n)
O
(
n
)
What are the different categories of running time complexity shown in the image?
O(1)
- Best
O(logn)
- Good
O(n)
- Fair
O(nlogn)
- Bad
O(n!)
, O(n^n),
O(n^c)
- Worst
What is Big O notation used for?
To measure
algorithm
runtime
changes
What is the y-axis label in the image?
Running Time Complexity
in terms of
Big-O
O(f(n))
What is the growth rate of
O
(
log
n
)
O(\log n)
O
(
lo
g
n
)
?
Logarithmic
What is the first search algorithm mentioned?
Linear Search
What is the time complexity of binary search?
O
(
log
n
)
O(\log n)
O
(
lo
g
n
)
What characterizes an efficient algorithm?
Completes tasks quickly
with
minimal resources
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